/*
 * Copyright (c) 2000 jPOS.org. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *  1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *  3. The end-user documentation included with the redistribution, if any,
 * must include the following acknowledgment: "This product includes software
 * developed by the jPOS project (http://www.jpos.org/)". Alternately, this
 * acknowledgment may appear in the software itself, if and wherever such
 * third-party acknowledgments normally appear.
 *  4. The names "jPOS" and "jPOS.org" must not be used to endorse or promote
 * products derived from this software without prior written permission. For
 * written permission, please contact license@jpos.org.
 *  5. Products derived from this software may not be called "jPOS", nor may
 * "jPOS" appear in their name, without prior written permission of the jPOS
 * project.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE JPOS
 * PROJECT OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 * 
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the jPOS Project. For more information please see
 * <http://www.jpos.org/> .
 */

package com.nasoft.iso;

/**
 * AsciiPrefixer constructs a prefix for ASCII messages.
 * 
 * @author joconnor
 * @version $Revision: 1.5 $ $Date: 2004/07/02 13:18:22 $
 */
public class AsciiPrefixer implements Prefixer
{
  /**
   * A length prefixer for upto 9 chars. The length is encoded with 1 ASCII char
   * representing 1 decimal digit.
   */
  public static final AsciiPrefixer L      = new AsciiPrefixer(1);
  /**
   * A length prefixer for upto 99 chars. The length is encoded with 2 ASCII
   * chars representing 2 decimal digits.
   */
  public static final AsciiPrefixer LL     = new AsciiPrefixer(2);
  /**
   * A length prefixer for upto 999 chars. The length is encoded with 3 ASCII
   * chars representing 3 decimal digits.
   */
  public static final AsciiPrefixer LLL    = new AsciiPrefixer(3);
  /**
   * A length prefixer for upto 9999 chars. The length is encoded with 4 ASCII
   * chars representing 4 decimal digits.
   */
  public static final AsciiPrefixer LLLL   = new AsciiPrefixer(4);
  /**
   * A length prefixer for upto 99999 chars. The length is encoded with 5 ASCII
   * chars representing 5 decimal digits.
   */
  public static final AsciiPrefixer LLLLL  = new AsciiPrefixer(5);

  /**
   * A length prefixer for upto 999999 chars. The length is encoded with 6 ASCII
   * chars representing 6 decimal digits.
   */
  public static final AsciiPrefixer LLLLLL = new AsciiPrefixer(6);

  // private static final LeftPadder PADDER = LeftPadder.ZERO_PADDER;
  // private static final AsciiInterpreter INTERPRETER =
  // AsciiInterpreter.INSTANCE;

  /** The number of digits allowed to express the length */
  protected int                       nDigits;

  public AsciiPrefixer(int nDigits)
  {
    this.nDigits = nDigits;
  }

  public AsciiPrefixer(){
	  this.nDigits=0;
  }
  /*
   * (non-Javadoc)
   * 
   * @see org.jpos.iso.Prefixer#encodeLength(int, byte[])
   */
  public void encodeLength(int length, byte[] b) throws ISOException
  {
    int n = length;
    
    // Write the string backwards - I don't know why I didn't see this at first.
    for (int i = nDigits - 1; i >= 0; i--)
    {
      b[i] = (byte) (n % 10 + '0');
      n /= 10;
    }
    
    
    if (n != 0)
    {
      throw new ISOException("invalid len " + length + ". Prefixing digits = "
          + nDigits);
    }
    
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.jpos.iso.Prefixer#decodeLength(byte[], int)
   */
  public int decodeLength(byte[] b, int offset)
  {
    int len = 0;
    for (int i = 0; i < nDigits; i++)
    {
    	len = len * 10 + b[offset + i] - (byte) '0';
    }
    return len;
  }

  /*
   * (non-Javadoc)
   * 
   * @see xcom.traxbahn.iso.Prefixer#getLengthInBytes()
   */
  public int getPackedLength()
  {
    return nDigits;
  }
}
